Risk factors for postoperative delirium following hip fracture repair in elderly patients: a systematic review and meta-analysis

Background No formal systematic review or meta-analysis was performed up to now to summarize the risk factors of delirium after hip surgery. Aims The present study aimed to quantitatively and comprehensively conclude the risk factors of delirium after hip surgery in elderly patients. Methods A search was applied to CNKI, Embase, Medline, and Cochrane central database (all up to August 2015). All studies assessing the risk factors of delirium after hip surgery in elderly patients without language restriction were reviewed, and qualities of included studies were assessed using the Newcastle-Ottawa Scale. Data were pooled and a meta-analysis was completed. Results A total of 24 studies were selected, which altogether included 5364 patients with hip fracture. One thousand and ninety of them were cases of delirium occurred after surgery, suggesting the accumulated incidence of 24.0 %. Results of meta-analyses showed that elderly patients with preoperative cognitive impairment [odds ratio (OR) 3.21, 95 % confidence interval (CI) 2.26-4.56), advanced age (standardized mean difference 0.50, 95 % CI 0.33-0.67), living in an institution (OR 2.94; 95 % CI 1.65-5.23), heart failure (OR 2.46; 95 % CI 1.72-3.53), total hip arthroplasty (OR 2.21; 95 % CI 1.16-4.22), multiple comorbidities (OR 1.37; 95 % CI 1.12-1.68) and morphine usage (OR 3.01; 95 % CI 1.30-6.94) were more likely to sustain delirium after hip surgery. Females were less likely to develop delirium after hip surgery (OR 0.83; 95 % CI 0.70-0.98). Conclusions Related prophylaxis strategies should be implemented in elderly patients involved with above-mentioned risk factors to prevent delirium after hip surgery.